1. Field
The following description relates to a source driver, a controller, and a method for driving a source driver that serve to generate a signal to read video data.
2. Description of the Related Art
A liquid crystal display (LCD) apparatus is an apparatus that converts video data into electric signals and inputs the electric signals. According to an electric driving signal applied to an LCD apparatus, pixels of a liquid crystal layer of the LCD apparatus are controlled to be in a light penetration state or a light interruption state by a transistor included in each of the pixels. Under such control, hundreds of thousands or millions of pixels constitute a single screen of an LCD apparatus.
A driving circuit needed in order to drive the LCD apparatus includes a gate driver to control an on-off state of a switching transistor, and a source driver to select a reference voltage of input video data and supply the reference voltage to a liquid crystal panel.
The source driver generally includes a controller, which receives a clock signal, a polarity conversion signal, and a start pulse signal from external sources. The start pulse signal is a signal to start to output the video data input to a shift register.
If a predetermined time elapses after the start pulse signal has been input, the controller of the related-art source driver generates a new start pulse signal and transmits the new start pulse signal to a source driver of a neighboring channel.
The LCD apparatus includes a plurality of source drivers. One source driver may generate a new start pulse signal and transmit the new start pulse signal to a source driver of a neighboring channel if a predetermined time elapses after the start pulse signal has been input.
For example, a source driver of a second channel outputs video data if it receives a start pulse signal generated by a source driver of a first channel. If a predetermined time elapses, the source driver of the second channel generates a new start pulse signal and transmits the new start pulse signal to a source driver of a third channel.
Through the above-described process, the plurality of source drivers included in the LCD apparatus outputs the video data in sequence.
However, the related-art LCD apparatus includes a configuration to input and output the start pulse signals among the source drivers. Accordingly, each of the start pulse signals is generated periodically and transmitted to the outside of the LCD apparatus.
Each of the start pulse signals may be generated with a predetermined period. Such signals generated with a period may become noise, being included in a frequency band of a baseband of 900 MHz of a wireless wide area network (WWAN). Therefore, in an apparatus including the WWAN and the LCD apparatus simultaneously, such as a notebook computer, wireless communication may be influenced by the start pulse signal.
Also, the start pulse signal may be generated as many as N−1 for each line of the LCD apparatus and as many as (N−1)×the number of lines for each frame. Therefore, power consumption increases and may cause aging and deterioration of the LCD apparatus.